1.1 --- /dev/null Thu Jan 01 00:00:00 1970 +0000
1.2 +++ b/src/share/vm/jfr/leakprofiler/chains/edgeUtils.cpp Mon Aug 12 18:30:40 2019 +0300
1.3 @@ -0,0 +1,312 @@
1.4 +/*
1.5 + * Copyright (c) 2014, 2018, Oracle and/or its affiliates. All rights reserved.
1.6 + * DO NOT ALTER OR REMOVE COPYRIGHT NOTICES OR THIS FILE HEADER.
1.7 + *
1.8 + * This code is free software; you can redistribute it and/or modify it
1.9 + * under the terms of the GNU General Public License version 2 only, as
1.10 + * published by the Free Software Foundation.
1.11 + *
1.12 + * This code is distributed in the hope that it will be useful, but WITHOUT
1.13 + * ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or
1.14 + * FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License
1.15 + * version 2 for more details (a copy is included in the LICENSE file that
1.16 + * accompanied this code).
1.17 + *
1.18 + * You should have received a copy of the GNU General Public License version
1.19 + * 2 along with this work; if not, write to the Free Software Foundation,
1.20 + * Inc., 51 Franklin St, Fifth Floor, Boston, MA 02110-1301 USA.
1.21 + *
1.22 + * Please contact Oracle, 500 Oracle Parkway, Redwood Shores, CA 94065 USA
1.23 + * or visit www.oracle.com if you need additional information or have any
1.24 + * questions.
1.25 + *
1.26 + */
1.27 +
1.28 +#include "precompiled.hpp"
1.29 +#include "classfile/javaClasses.hpp"
1.30 +#include "jfr/leakprofiler/chains/edge.hpp"
1.31 +#include "jfr/leakprofiler/chains/edgeStore.hpp"
1.32 +#include "jfr/leakprofiler/chains/edgeUtils.hpp"
1.33 +#include "jfr/leakprofiler/utilities/unifiedOop.hpp"
1.34 +#include "oops/fieldStreams.hpp"
1.35 +#include "oops/instanceKlass.hpp"
1.36 +#include "oops/objArrayOop.hpp"
1.37 +#include "oops/oopsHierarchy.hpp"
1.38 +#include "runtime/handles.inline.hpp"
1.39 +
1.40 +bool EdgeUtils::is_leak_edge(const Edge& edge) {
1.41 + return (const Edge*)edge.pointee()->mark() == &edge;
1.42 +}
1.43 +
1.44 +bool EdgeUtils::is_root(const Edge& edge) {
1.45 + return edge.is_root();
1.46 +}
1.47 +
1.48 +static int field_offset(const Edge& edge) {
1.49 + assert(!edge.is_root(), "invariant");
1.50 + const oop ref_owner = edge.reference_owner();
1.51 + assert(ref_owner != NULL, "invariant");
1.52 + const oop* reference = UnifiedOop::decode(edge.reference());
1.53 + assert(reference != NULL, "invariant");
1.54 + assert(!UnifiedOop::is_narrow(reference), "invariant");
1.55 + assert(!ref_owner->is_array(), "invariant");
1.56 + assert(ref_owner->is_instance(), "invariant");
1.57 + const int offset = (int)pointer_delta(reference, ref_owner, sizeof(char));
1.58 + assert(offset < (ref_owner->size() * HeapWordSize), "invariant");
1.59 + return offset;
1.60 +}
1.61 +
1.62 +static const InstanceKlass* field_type(const Edge& edge) {
1.63 + assert(!edge.is_root() || !EdgeUtils::is_array_element(edge), "invariant");
1.64 + return (const InstanceKlass*)edge.reference_owner_klass();
1.65 +}
1.66 +
1.67 +const Symbol* EdgeUtils::field_name_symbol(const Edge& edge) {
1.68 + assert(!edge.is_root(), "invariant");
1.69 + assert(!is_array_element(edge), "invariant");
1.70 + const int offset = field_offset(edge);
1.71 + const InstanceKlass* ik = field_type(edge);
1.72 + while (ik != NULL) {
1.73 + JavaFieldStream jfs(ik);
1.74 + while (!jfs.done()) {
1.75 + if (offset == jfs.offset()) {
1.76 + return jfs.name();
1.77 + }
1.78 + jfs.next();
1.79 + }
1.80 + ik = (InstanceKlass*)ik->super();
1.81 + }
1.82 + return NULL;
1.83 +}
1.84 +
1.85 +jshort EdgeUtils::field_modifiers(const Edge& edge) {
1.86 + const int offset = field_offset(edge);
1.87 + const InstanceKlass* ik = field_type(edge);
1.88 +
1.89 + while (ik != NULL) {
1.90 + JavaFieldStream jfs(ik);
1.91 + while (!jfs.done()) {
1.92 + if (offset == jfs.offset()) {
1.93 + return jfs.access_flags().as_short();
1.94 + }
1.95 + jfs.next();
1.96 + }
1.97 + ik = (InstanceKlass*)ik->super();
1.98 + }
1.99 + return 0;
1.100 +}
1.101 +
1.102 +bool EdgeUtils::is_array_element(const Edge& edge) {
1.103 + assert(!edge.is_root(), "invariant");
1.104 + const oop ref_owner = edge.reference_owner();
1.105 + assert(ref_owner != NULL, "invariant");
1.106 + return ref_owner->is_objArray();
1.107 +}
1.108 +
1.109 +static int array_offset(const Edge& edge) {
1.110 + assert(!edge.is_root(), "invariant");
1.111 + const oop ref_owner = edge.reference_owner();
1.112 + assert(ref_owner != NULL, "invariant");
1.113 + const oop* reference = UnifiedOop::decode(edge.reference());
1.114 + assert(reference != NULL, "invariant");
1.115 + assert(!UnifiedOop::is_narrow(reference), "invariant");
1.116 + assert(ref_owner->is_array(), "invariant");
1.117 + const objArrayOop ref_owner_array = static_cast<const objArrayOop>(ref_owner);
1.118 + const int offset = (int)pointer_delta(reference, ref_owner_array->base(), heapOopSize);
1.119 + assert(offset >= 0 && offset < ref_owner_array->length(), "invariant");
1.120 + return offset;
1.121 +}
1.122 +
1.123 +int EdgeUtils::array_index(const Edge& edge) {
1.124 + return is_array_element(edge) ? array_offset(edge) : 0;
1.125 +}
1.126 +
1.127 +int EdgeUtils::array_size(const Edge& edge) {
1.128 + if (is_array_element(edge)) {
1.129 + const oop ref_owner = edge.reference_owner();
1.130 + assert(ref_owner != NULL, "invariant");
1.131 + assert(ref_owner->is_objArray(), "invariant");
1.132 + return ((objArrayOop)(ref_owner))->length();
1.133 + }
1.134 + return 0;
1.135 +}
1.136 +
1.137 +const Edge* EdgeUtils::root(const Edge& edge) {
1.138 + const Edge* current = &edge;
1.139 + const Edge* parent = current->parent();
1.140 + while (parent != NULL) {
1.141 + current = parent;
1.142 + parent = current->parent();
1.143 + }
1.144 + return current;
1.145 +}
1.146 +
1.147 +// The number of references associated with the leak node;
1.148 +// can be viewed as the leak node "context".
1.149 +// Used to provide leak context for a "capped/skipped" reference chain.
1.150 +static const size_t leak_context = 100;
1.151 +
1.152 +// The number of references associated with the root node;
1.153 +// can be viewed as the root node "context".
1.154 +// Used to provide root context for a "capped/skipped" reference chain.
1.155 +static const size_t root_context = 100;
1.156 +
1.157 +// A limit on the reference chain depth to be serialized,
1.158 +static const size_t max_ref_chain_depth = leak_context + root_context;
1.159 +
1.160 +const RoutableEdge* skip_to(const RoutableEdge& edge, size_t skip_length) {
1.161 + const RoutableEdge* current = &edge;
1.162 + const RoutableEdge* parent = current->physical_parent();
1.163 + size_t seek = 0;
1.164 + while (parent != NULL && seek != skip_length) {
1.165 + seek++;
1.166 + current = parent;
1.167 + parent = parent->physical_parent();
1.168 + }
1.169 + return current;
1.170 +}
1.171 +
1.172 +#ifdef ASSERT
1.173 +static void validate_skip_target(const RoutableEdge* skip_target) {
1.174 + assert(skip_target != NULL, "invariant");
1.175 + assert(skip_target->distance_to_root() + 1 == root_context, "invariant");
1.176 + assert(skip_target->is_sentinel(), "invariant");
1.177 +}
1.178 +
1.179 +static void validate_new_skip_edge(const RoutableEdge* new_skip_edge, const RoutableEdge* last_skip_edge, size_t adjustment) {
1.180 + assert(new_skip_edge != NULL, "invariant");
1.181 + assert(new_skip_edge->is_skip_edge(), "invariant");
1.182 + if (last_skip_edge != NULL) {
1.183 + const RoutableEdge* const target = skip_to(*new_skip_edge->logical_parent(), adjustment);
1.184 + validate_skip_target(target->logical_parent());
1.185 + return;
1.186 + }
1.187 + assert(last_skip_edge == NULL, "invariant");
1.188 + // only one level of logical indirection
1.189 + validate_skip_target(new_skip_edge->logical_parent());
1.190 +}
1.191 +#endif // ASSERT
1.192 +
1.193 +static void install_logical_route(const RoutableEdge* new_skip_edge, size_t skip_target_distance) {
1.194 + assert(new_skip_edge != NULL, "invariant");
1.195 + assert(!new_skip_edge->is_skip_edge(), "invariant");
1.196 + assert(!new_skip_edge->processed(), "invariant");
1.197 + const RoutableEdge* const skip_target = skip_to(*new_skip_edge, skip_target_distance);
1.198 + assert(skip_target != NULL, "invariant");
1.199 + new_skip_edge->set_skip_edge(skip_target);
1.200 + new_skip_edge->set_skip_length(skip_target_distance);
1.201 + assert(new_skip_edge->is_skip_edge(), "invariant");
1.202 + assert(new_skip_edge->logical_parent() == skip_target, "invariant");
1.203 +}
1.204 +
1.205 +static const RoutableEdge* find_last_skip_edge(const RoutableEdge& edge, size_t& distance) {
1.206 + assert(distance == 0, "invariant");
1.207 + const RoutableEdge* current = &edge;
1.208 + while (current != NULL) {
1.209 + if (current->is_skip_edge() && current->skip_edge()->is_sentinel()) {
1.210 + return current;
1.211 + }
1.212 + current = current->physical_parent();
1.213 + ++distance;
1.214 + }
1.215 + return current;
1.216 +}
1.217 +
1.218 +static void collapse_overlapping_chain(const RoutableEdge& edge,
1.219 + const RoutableEdge* first_processed_edge,
1.220 + size_t first_processed_distance) {
1.221 + assert(first_processed_edge != NULL, "invariant");
1.222 + // first_processed_edge is already processed / written
1.223 + assert(first_processed_edge->processed(), "invariant");
1.224 + assert(first_processed_distance + 1 <= leak_context, "invariant");
1.225 +
1.226 + // from this first processed edge, attempt to fetch the last skip edge
1.227 + size_t last_skip_edge_distance = 0;
1.228 + const RoutableEdge* const last_skip_edge = find_last_skip_edge(*first_processed_edge, last_skip_edge_distance);
1.229 + const size_t distance_discovered = first_processed_distance + last_skip_edge_distance + 1;
1.230 +
1.231 + if (distance_discovered <= leak_context || (last_skip_edge == NULL && distance_discovered <= max_ref_chain_depth)) {
1.232 + // complete chain can be accommodated without modification
1.233 + return;
1.234 + }
1.235 +
1.236 + // backtrack one edge from existing processed edge
1.237 + const RoutableEdge* const new_skip_edge = skip_to(edge, first_processed_distance - 1);
1.238 + assert(new_skip_edge != NULL, "invariant");
1.239 + assert(!new_skip_edge->processed(), "invariant");
1.240 + assert(new_skip_edge->parent() == first_processed_edge, "invariant");
1.241 +
1.242 + size_t adjustment = 0;
1.243 + if (last_skip_edge != NULL) {
1.244 + assert(leak_context - 1 > first_processed_distance - 1, "invariant");
1.245 + adjustment = leak_context - first_processed_distance - 1;
1.246 + assert(last_skip_edge_distance + 1 > adjustment, "invariant");
1.247 + install_logical_route(new_skip_edge, last_skip_edge_distance + 1 - adjustment);
1.248 + } else {
1.249 + install_logical_route(new_skip_edge, last_skip_edge_distance + 1 - root_context);
1.250 + new_skip_edge->logical_parent()->set_skip_length(1); // sentinel
1.251 + }
1.252 +
1.253 + DEBUG_ONLY(validate_new_skip_edge(new_skip_edge, last_skip_edge, adjustment);)
1.254 +}
1.255 +
1.256 +static void collapse_non_overlapping_chain(const RoutableEdge& edge,
1.257 + const RoutableEdge* first_processed_edge,
1.258 + size_t first_processed_distance) {
1.259 + assert(first_processed_edge != NULL, "invariant");
1.260 + assert(!first_processed_edge->processed(), "invariant");
1.261 + // this implies that the first "processed" edge is the leak context relative "leaf"
1.262 + assert(first_processed_distance + 1 == leak_context, "invariant");
1.263 +
1.264 + const size_t distance_to_root = edge.distance_to_root();
1.265 + if (distance_to_root + 1 <= max_ref_chain_depth) {
1.266 + // complete chain can be accommodated without constructing a skip edge
1.267 + return;
1.268 + }
1.269 +
1.270 + install_logical_route(first_processed_edge, distance_to_root + 1 - first_processed_distance - root_context);
1.271 + first_processed_edge->logical_parent()->set_skip_length(1); // sentinel
1.272 +
1.273 + DEBUG_ONLY(validate_new_skip_edge(first_processed_edge, NULL, 0);)
1.274 +}
1.275 +
1.276 +static const RoutableEdge* processed_edge(const RoutableEdge& edge, size_t& distance) {
1.277 + assert(distance == 0, "invariant");
1.278 + const RoutableEdge* current = &edge;
1.279 + while (current != NULL && distance < leak_context - 1) {
1.280 + if (current->processed()) {
1.281 + return current;
1.282 + }
1.283 + current = current->physical_parent();
1.284 + ++distance;
1.285 + }
1.286 + assert(distance <= leak_context - 1, "invariant");
1.287 + return current;
1.288 +}
1.289 +
1.290 +/*
1.291 + * Some vocabulary:
1.292 + * -----------
1.293 + * "Context" is an interval in the chain, it is associcated with an edge and it signifies a number of connected edges.
1.294 + * "Processed / written" means an edge that has already been serialized.
1.295 + * "Skip edge" is an edge that contains additional information for logical routing purposes.
1.296 + * "Skip target" is an edge used as a destination for a skip edge
1.297 + */
1.298 +void EdgeUtils::collapse_chain(const RoutableEdge& edge) {
1.299 + assert(is_leak_edge(edge), "invariant");
1.300 +
1.301 + // attempt to locate an already processed edge inside current leak context (if any)
1.302 + size_t first_processed_distance = 0;
1.303 + const RoutableEdge* const first_processed_edge = processed_edge(edge, first_processed_distance);
1.304 + if (first_processed_edge == NULL) {
1.305 + return;
1.306 + }
1.307 +
1.308 + if (first_processed_edge->processed()) {
1.309 + collapse_overlapping_chain(edge, first_processed_edge, first_processed_distance);
1.310 + } else {
1.311 + collapse_non_overlapping_chain(edge, first_processed_edge, first_processed_distance);
1.312 + }
1.313 +
1.314 + assert(edge.logical_distance_to_root() + 1 <= max_ref_chain_depth, "invariant");
1.315 +}
